Biomechanical preparation of root canal / dental implant courses

BIO MECHANICAL
PREPARATION OF THE
ROOT CANAL
INDIAN DENTAL ACADEMY
Leader in continuing Dental Education
www.indiandentalacademy.com

 In an endodontic treatment, the root canal
system is our road map to success
 In the past, we have been thinking only
vertically. Many students were taught that
the first concern in root canal preparation
was “working length”. Now, we understand
that the critical issue is three-dimensionality.

 Almost 30 years ago, Schilder introduced the
concept “cleaning and shaping”.

Indian Dental academy
• www.indiandentalacademy.com
• Leader continuing dental education
• Offer both online and offline dental courses

 Refers to the removal of all contents of the root
canal system before and during shaping.
 Substrates, microflora, bacterial products, caries
etc.

 The final preparation of this system should be an
exact replica of the original canal configuration in
shape, taper, and flow only larger.

Filing:
 Indicates a push-pull action with the
instrument
 The inward passage of the file is powered by
the hand and the rigidity of the file.
 This is an effective technique with H-file
since they do not engage during the insertion
action and cut efficiently during the
withdrawal motion.

 Disadvantages:
◦ With H-file that it can easily cut the middle of a curvature
and cause strip perforation.

 Indicates clockwise / right-hand rotation of an
instrument.
 The instrument must be restrained from insertion
to generate a cutting effect

 Is a combination of reaming and filling, the file is
inserted with a ¼ turn clockwise and inwardly
directed hand pressure (i.e. reaming) positioned
into the canal by this action, the file is
subsequently withdrawn (i.e. filling).

 Is the back-and-forth oscilation of a file (30-60°)
right and (30-60°) left as the instrument is pushed
into the canal.
 This back-and-forth movement causes the files
and reamers to plane the walls efficiently.

 With each clockwise turn, the instrument moves
apically until it meets resistance and must be
freed with a pull stroke.
 Used with H-files

◦ insert an instrument, it is rotated to the right
(clockwise) a quarter turn. This pulls the instrument
into the canal and positions the cutting edges into
the walls.
◦ Next, it is rotated left (counterclockwise) at least
1/3rd of the revolution to unthread the instrument
and drive it from the canal.

Advantages:
◦ Simultaneous apical and counter-clockwise rotation
of file strikes a balance between the tooth structure
and instrument elastic memory. This balance locates
the instrument very near the canal axis, even in
severely curved canals, so this technique avoids
transportation.
◦ It works effectively without pre-curving.

 Done in narrow canals with circular cross-
sections.
WL determined.

Smallest instrument adjusted to WL.

Sequentially enlarged entire canal.

The canal is then obturated

Disadvantages:
 Risk of extrusion of debris.
 Alteration of WL.
 Vertical root # is possible if over instrumentation is
carried out.

WL determined.

Instrument that fills to correct WL is chosen.

Enlarge 3 No’s larger at the apex.

Reduce the WL length by 1mm and continue to
enlarge canal / flaring.

Recapitulate, irrigate for patency.

Coronal preparation done using GGD.

Step back
1. Phase I: Apical preparation starting at apical
constriction
2. Phase II: Preparation of reminder of canal
3. Phase IIA: Refining phase with Gates glidden
4. Phase IIB: Circumferential filing with No.25 file
5. Completed preparation

 Extrusion of debris.
 Apical blockage.
 Alteration of W.L.
 Tendency for canal deviations.

advantages
 Less lightly to like cause periapical
trauma.
 Development of apical matrix prevent over
filling.
 Greater condensation pressure can be
exerted.

 Balanced force technique was derived from the
physical law which states that “action and
reactions are equal and opposite”
 Develop instrumentation which has high
magnitude of forces against file, small magnitude
forces against the canal walls to develop a
balance of action to reaction.

 K-type files are preferably used in this
technique because of their cross section
(triangular)
 K-type design provides cutting edges with
identical rake and clearance angles
regardless of the direction of action
 They provide bi-directional cutting mechanism
without loss of efficacy

 Bi-direction refers to cutting efficacy
in
apical (insertion)
coronal (withdrawal)
clockwise rotation
counter clockwise rotation

Disadvantages
 Over extension and stripping of the inner walls of
the curved canals are the major disadvantages

Modified step back technique
Step back procedure begins 2-3mm up the
canal which provides almost retentive parallel
walls at the apex.

Passive step back Technique
Walton’s and Torabinejad technique(1994).
Combination of hand and rotary instrumentation.
Requires 10-40 No K-file,
2-3 No. GG drills,
2-3 No. Peeso reamers.

Technique involves 6 steps
1. Access opening and working length determination.
2. Passive step back hand instrumentation.
3. Passive use of GG drills
4. Confirmation of working length.
5. Passive use of GG drills and/or peeso reamers.
6. Apical preparation.

Ohio-State Technique
Enlargement of the apex to No.25
GG No. 2 for coronal 2/3rd
No. 30, 35 to the original working length
GG No. 3
No. 40 to the original working lengthwww.indiandentalacademy.com

Step down Technique
• Pre-Gates preparation
• Gates Glidden preparation
• Starting with larger instruments canal is
progressively enlarged apically 1-2mm until No.25
reaches CDJ

Disadvantages:
 Ledge formation.
 Apical blockage.
 Perforation.

 Albert C George in the year 1982 proposed this
technique which combines the step down and step
back techniques.
 The coronal portion is prepared by step down tech
and the apical preparation is completed with step
back.

Determine W.L.

Prepare till 14 mm / coronal to the curve.

Irrigate and clean.

Go 1mm deeper, maintaining instrumentation coronal to
the curve and file.

Again 1mm deeper.

Continue till WL is achieved.

Prepare using step-back

Indications:
 For straight canals or
 For straight portions of curved canals.
Contra indications:
 In calcified canals.
 In young permanent teeth with open apices.

 Canal master technique uses modified root canal
instrument in a coronal apical approach.
 The inst can be both hand held or mechanized.
 The apical 0.75mm of the hand instrument is safe-
ended to facilitate maintenance of canal curvature.

Determine WL

Prepare to the beginning of the curve with GG

Use canal master in step-back fashion to prepare
the rest of the canal

Root canal preparation using
Rotary cutting instruments
• Profile series
• Light speed
• Protaper

Profile series

Light speed

Protaper

Ultrasonic System
Richman introduced in 1957.
Barbed broaches were used first.
Now wide ranges of files with particles are used.

Mechanics
20 to 40 KHz of sound energy is used from electromagnetic
or piezo
Cavitation.
Synergistic action- chemical action of irrigant, abrasive
action of file.
Negative pressure within cells.

Advantages
Decreases operator time.
Faster root canal preparation.
Irrigation of root canal is more efficient.
Disadvantages
Corrosion of tips.
Zip formation

Sonic System
1500-6500 cycles/min.
Three types of files are used.
Rispi sonic, shaper sonic, heli sonic.

LASER preparation
first reported use by Weichmen &Johnson in 1971
they tried to seal the apical foramen by means of CO2
laser
150 mili joules laser energy is used.
Plasma effect is same.
CO2 laser of 10.6 micrometer is used.
Nd:YAG of 1.06 micrometer is used.
ArF excimer of 193 is used.

 Was introduced by Lussi et al in 1993
the technique uses a vacuum pump and an
electrically driven piston generating alternating
pressure and bubbles in the irrigation solution
inside the root canal
this expected to enhance the ability of NaOCl to
dissolve organic pulp tissue
following the cleansing procedure the root canal
may be obturated by the vacuum pump with a
sealer.

 In experimental studies done on extracted teeth
the mean percentage of teeth with tissue
remnants and remaining debris in the coronal
third of the root canal was shown to be 34.4%,
55.8 % in the middle third and 76.6% in the
apical part
 Additional intraoperative problems such as
severe pain under extension and apical extrusion
of sealer or breakdown of vacuum have been
reported

 In conclusion as the NIT system is presented not
marketed and long term observations are missing
it cannot be regarded as an alternative to the
mechanical root canal instrumentation

Biomechanical preparation of root canal / dental implant courses

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